The present invention relates generally to air bags of the type utilized in vehicle occupant restraint systems.
Motor vehicles commonly employ air bag systems to supplement the protection provided by seatbelts. These air bag systems use at least one folded air bag in fluid communication with a source of inflation gas. When a collision is detected, a sensor within the vehicle actuates the source of inflation gas. Typically, a chemical reaction generates the inflation gas needed to inflate the air bag. Consequently, the air bag rapidly expands to absorb at least a portion of the collision force that would otherwise have been imparted to the vehicle occupant.
Motor vehicles often contain several air bags, with each air bag positioned in an area of vulnerability for the vehicle occupants. The steering wheel generally contains a driver's side air bag to protect the driver. To protect an occupant located in the front passenger seat, the dash usually houses a passenger side air bag. In addition to driver side and passenger side air bags, many vehicles are now being equipped with side curtains.
Coated air bag fabrics were originally used for the driver's side air bags to inhibit the penetration of hot gases and particulate through the surface of the cushion. These air bags consisted primarily of neoprene rubber coated 840-denier, 25×25 construction nylon fabrics. The coating weight was typically about 2 ounces per square yard. Accordingly, these fabrics were very heavy and not easily packed into the small modules which contain the air bag system.
During the 1980's, the neoprene coated 840-denier fabrics were eventually phased out and replaced with a lighter weight silicone coated 420-denier 49×49 or 46×46 construction fabric. The silicone currently in production in the U.S. is either wholly solids with no solvents, or may contain some solvents which are burned off in ovens after the coating is applied. Regardless of the chemistry, silicone is typically applied in a knife over roll application on one side of the fabric, followed by heated ovens that are required for curing.
With the inception of side curtain air bags, air-holding requirements have forced fabric suppliers to look at lamination as a means for meeting the new specifications. Side curtains differ from frontal air bags in that they must hold air for long periods to protect the occupants during a rollover event. Although silicone-coated bags are used in some instances, lamination also produces a very strong, airtight bag. The lamination process, however, is even more costly than silicone coating since it requires the application of a film, which is typically bonded to the fabric with an adhesive and then cured.
There exists a need for a novel air bag fabric which overcomes the aforementioned deficiencies.